Apparatus for collecting samples of drill cuttings and method of use

ABSTRACT

An apparatus and a method for surface logging include a vacuum assisted transfer of drill cuttings from a shale shaker to sample jars. The cuttings samples are used for measurements to characterize formations in which a wellbore is drilled. The apparatus has an adjustable suction line that can be used to control moisture on the surface of the drill cuttings fragments. The method includes an automated sample collection and a high throughput sample treatment (e.g., washing or/and a controllable drying) to increase value of measurements.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to a provisional patent application claiming the benefit 35 USC 119(e). The provisional patent application number is U.S. Pat. No. 62/696,821; filing date is Jul. 11, 2018.

BACKGROUND OF THE INVENTION Field of the Invention

This invention is related to an automated process of collecting drill cuttings at a shale shaker during the drilling operation. More specifically, the invention teaches apparatus and methods for fast automated sampling and preparation of the drill cuttings to enable continuous evaluation of petrophysical properties (e.g., properties evaluated based on natural gamma spectroscopy and nuclear magnetic resonance relaxometry) of the earth formations while drilling an oil well.

Background Art

Cost efficient drilling operation would greatly benefit from lower cost and high throughput quantitative data acquisition to evaluate the rock formations being drilled. Advanced mud logging including measurements on drill cuttings (e.g., using the spectroscopic techniques like XRF, XRD, NGS and NMR relaxometry) is an efficient approach to formations evaluation while drilling. These measurements are typically performed in laboratory, the throughput and functionality of these measurements may not be adequate to support the drilling process.

Implementation of the advanced mud logging may require a technique for fast drill cuttings sample collection and preparation. U.S. Pat. Nos. 6,386,026B1, 6,845,657B2, 8,276,686B2 and 9,920,623B1 teach different apparatus and methods for automated sampling of the drill cuttings.

None of the prior art above address practical aspects of the drill cuttings sampling and preparation needed to enable quantitative high throughput measurements. Therefore, an adequate technique for the drill cuttings samples collection and preparation is still needed.

BRIEF SUMMARY OF THE INVENTION

One aspect of the present invention is an apparatus for collecting samples of drill cuttings using vacuum assisted cuttings transfer from a shale shaker to a sample jar, the apparatus comprising a movable inlet port, a suction line to transfer cuttings from the inlet port to a discharge chamber, the suction line being adjustable to control surface moisture of the drill cuttings. The apparatus may further comprise a set of pneumatic actuators to control position of the inlet port and the sample jar and an electronics unit placed in an explosion-proof enclosure. The apparatus may comprise a vacuum control unit including an air operated (non-electric) vacuum pump. The apparatus further comprises a jar cassette for empty jars and a samples collection tray, the tray collecting the jars filled with the drill cuttings. The apparatus may comprise an at least one machine vision device to monitoring the amount of the drill cuttings at the movable inlet or providing the cuttings sample description. The apparatus may comprise an automated sample treatment unit comprising means for a simultaneous treatment of a plurality of the drill cuttings samples in the sample jars, the treatment including at least one of (i) washing the sample and (ii) at least partly drying the cuttings sample.

Another aspect of the present invention is a method for collecting samples of drill cuttings, the method comprising transferring the drill cuttings from the shaker using a vacuum assisted flow via a suction line, at least partly, removing residual fluids from the drill cuttings surface, the residual fluids controlled by the cuttings travel regime in the suction line and/or geometry of the suction line. The method further comprises collecting the drill cuttings samples in the sample jars on a sample tray and using the samples for measurements to characterize rock formations, in which a wellbore is drilled. The measurements may include natural gamma spectroscopy and/or nuclear magnetic resonance relaxometry. The method may include a step of placing the sample tray into an automated sample preparation unit to perform at least one of (i) automated washing the cuttings, with a fluid, (ii) controllable drying the cuttings and (iii) filling the space between the cuttings fragments in the jar with a fluid having known properties.

Yet another aspect of the present invention is a method of surface logging using measurements on drill cuttings including collecting a plurality of drill cuttings samples in sample jars and treating the plurality of drill cuttings samples before the measurements, the treating conducted automatically on the plurality of the drill cuttings samples. The measurements are to be used for formations evaluation purposes. The treating may include an at least one of (i) automated washing the cuttings, with a fluid, (ii) controllable drying the cuttings and (iii) filling the space between the cuttings fragments in the jar with a fluid having known properties. The measurements comprise bulk sensitive measurements including an at least one of (i) natural gamma spectroscopy and (ii) nuclear magnetic resonance relaxometry.

Other aspects and advantages of the present disclosure will be apparent from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a conceptual view of the apparatus of the present invention.

FIG. 2 is a partial isometric view of apparatus of present invention illustrating the cuttings sample transfer unit according to embodiments disclosed.

FIG. 3A and FIG. 3B represent different isometric views of an automated sample preparation unit.

FIG. 4 illustrates a method of present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a conceptual view of the apparatus of the present invention. The apparatus comprises a cuttings transfer unit 100 including a cuttings inlet port 103 to acquire cuttings from the surface of a shaker 102 or, alternatively, from a cuttings receiving board (the cuttings entering the inlet port are shown at 104), a cuttings inlet port displacement actuator 106 to scan the surface of the shake during the cuttings acquisition from the shaker surface, and an adjustable suction line 109 (flexible, with adjustable length) to transfer cuttings from the inlet port to the discharge chamber 110. The adjustable suction line is also used to substantially eliminate (or reduce as needed) moisture on the surface of the cuttings fragments. The moisture is reduced during transferring cutting in the suction line. The length of the line controls the level of the moisture reduction. The moisture control is required for some measurements on drill cutting, for example, for nuclear magnetic resonance relaxometry. The cuttings flow direction is shown at 107 and the moisture (and, possibly, dust) flow direction is shown at 108 (the directions 107 and 108 are the same inside the suction line 109). The apparatus further comprises a vacuum control unit 112 connected to the discharge chamber 110 (shown at 113 is the direction of the pressure gradient). The unit 112 preferably includes a vacuum port, a vacuum line and an air operated (non-electric) vacuum pump (these elements are not shown in FIG. 1). The cuttings sample is collected (via the cuttings exit port 111) in the cuttings sample jar shown at 114. During the cutting transfer and filling the jar with the cutting sample, the jar is connected to the discharge chamber and is a part of the vacuum circuit. Shown at 116 is a module comprising pneumatic actuators and controls (including pressure line, valves and other elements that are partly shown in FIG. 2 below) to move an empty sample jar from a jar cassette 118 to the cuttings exit port 111 and then to a samples collection tray 120 (several sample collection trays are typically used in the apparatus). Each jar has a sample identification code (e.g. a barcode or a radio-frequency identification tag). Different units of the apparatus are controlled by control electronics 122. The electronics is placed in an explosion-proof enclosure, which is hermetically sealed and filled with pressured nitrogen to avoid or mitigate accidental penetration of flammable vapors (that may be present near the shaker) inside the measurement module. The control electronics preferably has automated electric circuit breakers if the nitrogen pressure drops below a certain level. All electrical lines associated with the control electronics are placed in the same pressure circuit.

The apparatus may include a machine vision and processes monitoring unit 124 to monitor the presence and quantity of cuttings on the shaker, to monitor the status of subsystems and processes during the operation. The unit 124 includes sensors needed to monitor the processes, for example a set of sensors may be used to monitor pressure in suction line, discharge chamber and vacuum control unit (e.g., in vacuum line). A set of pressure sensors may also be used to monitor the nitrogen pressure and use the readings as a feedback to control the electrical circuit breakers. The unit 124 preferably includes a machine vision device (not shown separately in FIG. 1). The device may be used to assess properties of the drill cuttings to provide the cuttings sample description, e.g., the color of the sample, the grain size and distribution, the grain shape (the information may be used to characterize the earth formations being drilled). The machine vision device may comprise different sources of the sample illumination including a natural light or a lamp with a “blue” light or blue filter. Proper illumination is required so that the true colors of the sample constituent minerals are not distorted. The machine vision device may also use a source of ultraviolet (UV) light to view the sample and detect any fluorescence that may be then attributed to some mineral or hydrocarbon. The unit 124 further includes a sample identification code reader that reads the code on each sample and the data are saved in the log file with the time marker to synchronize time of sample collection with the clock on the well side and, eventually, with the depth of origin of the cuttings samples.

In a preferred embodiment, the apparatus further comprises an automated sample treatment unit 126 described further below (FIG. 3A, FIG. 3B).

FIG. 2 is a partial isometric view of apparatus of present invention illustrating the cuttings sample transfer according to embodiments disclosed. Shown in FIG. 2 is the shaker 102, the cuttings inlet port 103, and the cuttings inlet displacement actuator 106 (to scan the surface of the shaker to collect cuttings directly from the shaker). Alternatively, the cuttings may be collected from a receiving board (not shown in FIG. 1 and FIG. 2). The cuttings are transferred via the suction line 109 to the discharge chamber 110 as explained above. A set of pneumatic actuators is used to move an empty sample jar from the cassette 118 to the discharge chamber 110 where the jar is filled with the cuttings via the cuttings exit port 111. Then the jar with the cuttings is transferred to a samples collection tray 120 (a plurality of the sample collection trays is preferably used). The set of pneumatic actuators includes: an actuator 1 (202) to catch the empty jar from the cassette 118, an actuator 2 (204) for displacement of the empty jar, an actuator 3 (206) for rotation of the jar about a horizontal axis, an actuator 4 (208) for rotation of the jar about the vertical axis, an actuator 5 (210) to vertically move the jar to connect it to the discharge chamber, and an actuator 6 (212) to move vertically the arm of the actuator 2. It would be readily understood by a person with ordinary skills in the art that the operations described above can be implemented in different ways. It is important though that the operations are performed using pneumatic (non-electric) actuators. Having non-electric actuators makes it easier to meet safety requirements (explosion-proof) for the apparatus deployed in the area near the shaker. Shown at 214 in FIG. 2 is an air operated (non-electric) vacuum pump (a part of the vacuum control unit 112).

FIG. 3A and FIG. 3B represent different isometric views of an automated sample treatment (preparation) unit 126. The FIG. 3A presents the main parts of the unit. The tray with the sample jars (with no caps) 302 is placed into the basket 304 and closed with the cover 306. The cover comprises the inlets 308 for a fluid or hot air. The fluid or air is transferred into the tubes 310 (at least one per jar). The cover 306 is tightened with the fasteners 312. The fluid or air exits via the holes 314 in the cover 306. FIG. 3B shows the assembled unit. After the samples treatment the cover is removed, and the jars are covered with leak-free caps.

FIG. 4 illustrates a method of present invention. The method comprises a step 410 of transferring the drill cuttings from the shaker using a vacuum assisted flow via a suction line. The transferring may include a quantitative description of the cuttings sample including describing the color, fluorescence, the grain size and the grain shape. The description may be done just before the cuttings enters the cuttings inlet port 103 or while the cuttings sample is in the suction line, the suction line walls may be made light transparent. The method includes a step 420 of partly or completely removing the surface moisture from the cuttings fragments, the residual moisture (and, possibly, dust) is controlled by adjusting the suction line length, a step 430 of delivering the cuttings into a sample jar and collecting the sample jars with cuttings on one or more sample trays. The method may include the step 432 of placing the sample tray into the automated samples treatment (preparation) unit (126) to perform at least one of (i) automated washing the cuttings, with a fluid and (ii) controllable drying the cuttings and (iii) filling the space between the cuttings fragments in the jar with a fluid with known properties. The steps related to controllable drying, washing, and filling may be required, for example, for nuclear magnetic resonance (NMR) measurements on drill cutting and natural gamma-ray spectroscopy (NGS) on drill cuttings. For example, residual fluid (e.g. moisture) on the surface of the cuttings fragments may interfere with the NMR measurements that target fluids properties in the pore space of the cuttings fragments. Washing cutting, for example, to remove clay particles from the drilling mud helps to avoid undesired Potassium signal in NGS measurements when a concentration of the Potassium present in a rock formation is measured. Filling the inter-fragment space in the cutting sample with a known fluid may be needed to determine a volume of cuttings using NMR. The volume is determined by subtracting the fluid volume (from NMR measurement) from the volume of the sample jar.

After performing the step 432, the method may include the step 434 of performing quantitative description of the cuttings samples including describing the color, fluorescence, the grain size and the grain shape. The quantitative description may be performed using a machine vision device. The machine vision device may comprise different sources of the sample illumination including a natural light or a lamp with a “blue” light or blue filter. Proper illumination is required so that the true colors of the sample constituent minerals are not distorted. The machine vision device may also use a source of ultraviolet (UV) light to view the sample and detect any fluorescence that may be then attributed to some mineral or hydrocarbon. The method further includes a step 440 of placing leak-proof caps on the jars and using the cuttings samples collected inside the jars in measurements intended to characterize the rock formations represented by the drill cuttings. The measurements are preferably performed at the well site to support drilling operation. The measurements may include high throughput bulk sensitive measurements (e.g., NMR relaxation and NGS measurements) that substantially does not require a sample preparation (the controllable moisture removal in step 420 may be sufficient). In this case the step 440 is performed directly after the step 430.

A step 442 may be additionally performed, in which the cuttings samples is placed in the sample treatment unit 126 again after the step 440 to perform treatment that substantially irreversibly modifies the sample, for example, using a solvent. The step 442 may include a quantitative sample description done with the jar cap removed or via the cap if a light transparent cap is used. The sample after the treatment may be subjected to another round of measurement presented by the step 440 in order to use the data before and after the treatment to further (better) characterize the rock formations while drilling.

The machine vision devices that may be employed in steps 410, 434 and 442 preferably use a pattern recognition based processing.

While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefits of this disclosure, will appreciate that other embodiments can be devised (particular illustrative embodiments disclosed above may be altered combined, or modified), which do not depart from the scope of invention as disclosed herein. The apparatus and methods illustratively disclosed herein may be practiced in the absence of any element that is not specifically disclosed herein and/or any optional element disclosed herein. 

What is claimed is:
 1. An apparatus for collecting samples of drill cuttings using vacuum assisted cuttings transfer from a shale shaker to a sample jar, the apparatus comprising: a movable inlet port; a suction line to transfer cuttings from the inlet port to a discharge chamber; a set of actuators to control position of the inlet port and the sample jar; and an electronics unit.
 2. The apparatus of claim 1, further comprising a vacuum control unit, the vacuum control unit including an air operated (non-electric) vacuum pump.
 3. The apparatus of claim 1, wherein the set of actuators includes pneumatic actuators.
 4. The apparatus of claim 1, wherein the electronics unit is placed in an explosion-proof enclosure, the enclosure having a hermetic seal and a pressured nitrogen to avoid accidental penetration of flammable vapors inside the enclosure.
 5. The apparatus of claim 1 further comprises a jar cassette for empty jars and a collection tray, the tray collecting the jars filled with the drill cuttings.
 6. The apparatus of claim 1, wherein the jar has a sample identification code.
 7. The apparatus of claim 1 further comprises an at least one machine vision device.
 8. The apparatus of claim 7, wherein the at least one machine vision device is used for at least one of (i) monitoring the amount of the drill cuttings to be collected by the movable inlet and (ii) providing the cuttings description.
 9. The apparatus of claim 1 further comprises an automated sample treatment unit.
 10. The apparatus of claim 9, wherein the sample treatment unit comprises means for a simultaneous treatment of a plurality of the drill cuttings samples, the treatment including at least one of (i) washing the sample and (ii) at least partly drying the sample.
 11. The apparatus of claim 1 further includes sensors to monitor an at least one of (i) a pressure in the suction line, (ii) a pressure in a discharge chamber, (iii) a pressure in the vacuum control unit and (iv) the nitrogen pressure.
 12. The apparatus of claim 1, wherein the suction line is adjustable to control surface moisture of the drill cuttings.
 13. A method for collecting samples of drill cuttings, the method comprising: transferring the drill cuttings from a shaker using a vacuum assisted flow via a suction line; collecting the drill cuttings samples in sample jars; and using the samples for measurements to characterize formations in which a wellbore is drilled.
 14. The method of claim 13 further comprises a step of at least partly removing residual fluids from the drill cuttings surface, the residual fluids controlled by adjusting geometry and/or regimes of the suction line;
 15. The method of claim 13, wherein the step of transferring includes a quantitative description of the cuttings.
 16. The method of claim 13, wherein the measurements comprises bulk sensitive measurements at a well site, the bulk sensitive measurements including at least one of (i) natural gamma spectroscopy and (ii) nuclear magnetic resonance relaxometry.
 17. The method of claim 13 further comprises a step of placing the sample tray into an automated sample preparation unit to perform at least one of (i) automated washing the cuttings, (ii) controllable drying the cuttings and (iii) filling the space between the cuttings fragments in the sample jar with a fluid having known properties.
 18. A method of surface logging using measurements on drill cuttings, the method comprising: collecting a plurality of drill cuttings samples in sample jars; treating the plurality of drill cuttings samples before the measurements, the treating conducted automatically on the plurality of the drill cuttings samples; and using the measurements to evaluate formations.
 19. The method of claim 18, wherein the treating includes an at least one of (i) automated washing the cuttings, (ii) controllable drying the cuttings and (iii) filling the space between the cuttings fragments in the jar with a fluid having known properties.
 20. The method of claim 18, wherein the measurements comprise bulk sensitive measurements including an at least one of (i) natural gamma spectroscopy and (ii) nuclear magnetic resonance relaxometry. 